Background information relating to the inventive technologies described herein will be summarized in this section. In addition, the following references provide further background information for the interested reader:    3GPP2 S.P 0126-0 System Requirements for femto Cell Systems;    “Universal Geographical Area Description (GAD)” Document ID: 3GPP TS 23.032 V7.0.0 (published 2006-06);    U.S. patent application Ser. No. 11/607,420, filed Dec. 1, 2006, entitled “System for Automatically Determining Cell Transmitter Parameters to Facilitate the Location of Wireless Devices” (published as U.S. 20080132247A1);    U.S. patent application Ser. No. 11/948,244, filed Nov. 30, 2007 “Automated Configuration of a Wireless Location System”; and    TR-069, “CPE WAN Management Protocol 1.1” DSL Forum.
Since the advent of cellular telecommunications in 1984, and especially in the past decade, the cellular industry has increased the number of air interface protocols available for use by wireless telephones, increased the number of frequency bands in which wireless or mobile telephones may operate, and expanded the number of terms that refer or relate to mobile telephones to include “personal communications services,” “wireless,” and others. The air interface protocols now used in the wireless industry include AMPS, N-AMPS, TDMA, CDMA, GSM, TACS, ESMR, GPRS, EDGE, UMTS WCDMA, and others.
The term CDMA will be used to refer to the CDMA digital cellular (TIA/EIA TR-45.4 defined IS-95, IS-95A), Personal Communications Services (J-STD-008), and 3GPP2 defined CDMA-2000 and UMB standards and air interfaces. The term UMTS will be used to refer to the 3GPP specified Wideband-CDMA (W-CDMA) based Universal Mobile Telecommunications System, defining standards, and radio air interface. The term WiMAX is used to denote the IEEE defined 802.16, “Broadband Wireless”; 802.20, “Mobile Broadband Wireless Access”; and 802.22, “Wireless Regional Area Networks” technologies. The present invention also applies to the in-progress 3GPP defined Long-Term-Evolution (LTE) and the 3GPP LTE Advanced system among others.
Wireless base stations, also sometimes called Access Points, are the radio connection point for analog or digital cellular frequency reuse systems such as personal communications systems (PCS), enhanced specialized mobile radios (ESMRs), wide-area-networks (WANs), and other types of wireless communications systems. The other end of the radio communications link will be referred to as the mobile or mobile device, which may be a mobile, portable or fixed device.
As the number of wireless communications protocols have grown, so has the number of types of base stations (sometimes called base transceiver stations, or BTS). Originally, cells (now called macro-cells) were deployed according to a detailed geographic, topographic and radio frequency propagation models to provide maximum coverage areas. Macro-cell base stations have typical power output ranges from the 10's to 100's of Watts. As the usage increased, channels were added to the existing base stations and new base stations were added. To limit interference between base stations, antenna down-tilt and transmit power levels were adjusted and radio frequency propagation modeling was used to increase the frequency reuse ratio from 12 to 7, 4, 3 and even 1 in some cases.
Smaller cells (micro-cells) with lower radio power outputs and smaller installation footprints were deployed to provide capacity where needed. In some markets, an overlay/underlay scheme of macro-cells and micro-cells were created to maximize capacity and geographic coverage. micro-cells provide radio coverage over short ranges, typically from 300 to 1000 meters, and have lower output radio power compared to macro-cells, usually a few Watts. These macro/micro cell network solutions also had the virtue of limiting inter-BTS handoffs for fast moving mobile devices. As coverage requirements became more rigorous, even smaller and lower power base stations (pico-cells) were deployed to cover dead zones and provide capacity in high-traffic areas. A pico-cell radio power output is nominally less than 1 Watt.
The latest base station species is the femto-cell. A femto-cell differs from previous base station species in that a femto-cell is a portable, consumer deployed unit typically using licensed spectrum. Unlike the traditional base station, backhaul to the wireless communications network is via a consumer provided packet data (IP) connection rather than the dedicated or leased line switched circuit backhaul used in first and second generation cellular systems. Designed for indoor coverage, femto-cell radio power output nominally ranges from 0.5 to 0.1 Watt. femto-cells are also known as “Home eNode B's” in the Third Generation Partnership Program's (3GPP) Long Term Evolution (LTE) or Evolved UTRAN (eUTRAN) program.
Using consumer installed femto-cells as a low cost approach to adding coverage and capacity to the wireless communications network raises some difficulties that embodiments of the present invention seek to address. The femto-cell base station can be a temporary, portable, and consumer controlled device but it uses spectrum licensed to the wireless communications provider (WCP); therefore, radio frequency use and power should be managed to both allow the femto-cell to function and to minimize interference with the wireless communications network, including other femto-cells. Proposed femto-cell management protocols, such as the DSL Forum's TR-069, “CPE WAN Management Protocol 1.1”, serve to auto-discover, provision and manage femto-cells but do not supply the femto-cell location. Also, since mobile devices using the femto-cell base station capacity should be able to use emergency services, the location of the femto-cell, if not the mobile device itself, should be provided in accordance to the United States Federal Communications Commission (FCC) mandate. To limit interference, early femto-cells will be able to listen to the surrounding radio environment and configure themselves automatically to minimize interference with the macro wireless communications network and other nearby femto-cells. Although some operator deployments may also use a distinct spectral band for femto-cells and thus limit interference with the wide-area radio communications network, femto-cell location may still be required by the FCC E911 Phase 2 mandate.
In one already described scenario, using the downlink receiver subsystem (as described in U.S. patent application Ser. No. 11/736,868, “Sparsed U-TDOA Wireless Location Networks,” and expanded in U.S. patent application Ser. No. 11/948,244, “Automated Configuration of a Wireless Location System”) of a network-based UTDOA wireless location system, location of stationary and mobile cells (including macro, micro, Pico, and femto-cells) can be acquired via detection and processing of the broadcast beacon(s). The broadcast beacon commonly implemented as a channel, or set of channels, in wireless radio access networks (GSM: BCCH, UMTS: BCH [PCCPCH], and CDMA: Broadcast Control Channel and pilot channel) allows mobile phones to discover geographically local base stations.
Overlay Network-based location solutions use specialized receivers and/or passive monitors within, or overlaid on, the wireless communications network to collect uplink (mobile device-to-base station) signals, which are used to determine location and velocity of the mobile device. Overlay Network-based techniques include uplink Time-Difference-of-Arrival (TDOA), Angle-Of-Arrival (AOA), Multipath Analysis (RF fingerprinting), and signal strength measurement (SSM).
Mobile-device based location solutions use specialized electronics and/or software within the mobile device to collect signaling. Location determination can take place in the device or information can be transmitted to a landside server which determines the location. Device-based location techniques include CID (serving Cell-ID), CID-RTF (serving cell-ID plus radio time-of-flight time-based ranging), CIDTA (serving cell-ID plus time-based ranging), Enhanced Cell-ID (ECID, a serving cell, time-based ranging and power difference of arrival hybrid), Advanced-Forward-Link-Trilateration (AFLT), Enhanced Observed Time Difference (E-OTD), Observed-Time-Difference-of-Arrival (OTDOA) and Global Navigation Satellite System (GNSS) positioning. An example of a GNSS system is the United States NavStar Global Positioning System. Hybrids of the network-based and mobile device-based techniques can be used to generate improved quality of services including improved speed, accuracy, yield, and uniformity of location. A wireless location system determines geographic position and, in some cases, the speed and direction of travel of wireless devices. Wireless location systems use uplink (device-to-network) signals, downlink (network-to-device) signals, or non-communications network signals (fixed beacons, terrestrial broadcasts, and/or satellite broadcasts). Network-based location solutions use specialized receivers and/or passive monitors within, or overlaid on, the wireless communications network to collect signaling used to determine location. Network-based techniques include uplink Time-Difference-of-Arrival (TDOA), Angle-Of-Arrival (AOA), Multipath Analysis (RF fingerprinting), and signal strength measurement (SSM). Hybrids of the network-based techniques can be used to generate improved quality of services including speed, accuracy, yield, and uniformity of location.